Dr. Slovin Discusses History of Immunotherapy in Prostate Cancer

Susan F. Slovin, MD, PhD, a medical oncologist at Memorial Sloan Kettering Cancer Center, discusses the history of immunotherapy in the treatment of patients with prostate cancer.

Prostate cancer was the first solid tumor to have an indication for an immunotherapy product, which was sipuleucel-T (Provenge). Ironically, it appears that the disease is not as immunologically robust as researchers thought, Slovin says. The field has been very fortunate that prostate cancer responds well to hormone therapy, but the idea that you can take a patient’s dendritic cells and educate them in culture to naturally fight the cancer was, at the time, a novel idea.

Immunotherapies have been around for almost a decade, Slovin notes, in forms like peptide vaccines, DNA vaccines, and combination vaccines with radiation and chemotherapy. None of those approaches showed much survival benefit, at least nowhere near what has recently been seen with checkpoint inhibitors in other solid tumors. With sipuleucel-T, patients had a modest survival benefit but there was no clear antitumor activity. Thus, patients who had high-volume disease would continue to progress.

Researchers also thought PROSTVAC, a novel platform of DNA transgenes, would change the landscape. Early data were promising, but the phase II study did not live up to the expectation of overall survival and antitumor effects.